Gear



E. WELDHABER GEAR Original Filed May 11. 1925 4 Sheefisfiheei: 2

Zdhaker ATTKTJRNEY R M my E. WiLQHABER GEAR Original Filed May ll, 1925 4 sheets fiheat 4 BNVENTGR E BY a? Wild MTQR NEY Patented Nov. 1, 1927;

UNITED STATES PATENT OFFICE.

ERNEST WILDHABER, OF ROCHESTER, NEXV YORK. ASSIGNOR T0 GLEASON WORKS, 01' ROCHESTER, NEW YORK. A CORPORATION OF NEW YORK.

GEAR.

1926. Serial No. 92,168.

Original application filed May 11, 1925, Serial No. 29.553. Divided and this application filed March at.

The present invention relates to gears and .in particular to gears which operate with axes non-intersecting and non-parallel.

One object of the present invention .is to provide a pair of gears. having axes nonintersecting and non-parallel. which shall have improved efficiency and improved tooth contact.

A further objectof this invention is to provide gears of this type with teeth of such shape that they may be accurately finished and readily ground.

Other objects are to provide a pair of gears, having axes non-intersecting and nonparallel, which is capable of accurate and rapid manufacture, which will be quiet in operation, which will wear evenly and which will have a high ratio of efficiency.

Other objects of the invention will appear in the course of the specification and from the appended claims.

lVith the above and other objects in view my invention resides in the various novel features peculiar tothe new type of gears and whic i are described in the specification, illustrated in the accompanying drawings and set forth in the claims appended hereto. This application is a division of my copending application Serial No. 29,553, filed May 11. 15-325.

In the drawings:

Figs. 1 and 2 are diagrammatic views. illustrative of the theory upon which the de termination of the proportions of the new gears is based;

Fig. 3 is a diagrammatic view showing the development of a pair of gears. constructed according to this invention. in a plane tange'pt to their respective pitch surfaces at a common contact point; V

Fig. 4 is a plan view of a pair pf gears constructed according to one embodiment of my invention;

, Fig. 5'is a side elevational view. partly, in section. of the pair of gears shown in Fig. 4;

Figs. 6 and 7 are diagrammatic views. similar to Fig. 3, showing the developed pitch surfaces of gears constructed according to two different embodiments of my invention. (These views are taken in a plane corresponding to the plane of Fig. 3.)

Fig Q, is a plan view of a pair of gears "cording tothis invention.

- Hypord or hypcrboloidal gears are gears which are adapted to mesh with their axes non-intersecting and non-parallel and in which at least one member of the pair is provided with teeth on a side face. @ne or both members of a pair of such gears is or are cut from a conical or crown blank. These gears have a zone of action which is outside the shortest. connecting line between their axes. While gears of this type. as heretoforc produced. have had the advantage that the axes of the driving and driven member might be offset one from the other, to

permit of drives not possible with bevel gears. this advantage has been offset in gear pairs of this type as heretofore produced by the noise of the gears in operation, the general weakness of the smaller member of the pair. and the difiiculty experienced in manufacturing them.

The present invention aims to overcome the ditficulties heretofore encountered in the design and production of h oid gears, as well asto provide a superior tooth form. According to this invention, gears of such proportions are provided. that the teeth have a gradual mesh and Contact along the en tire tooth surface of one member of the pair. The teeth of the pinion will match the tooth spaces of the gear substantially along their entire length and the teeth of gear and pinion will slide endwise upon one another in mesh. The combined rolling and sliding action of the new gears, as contrasted with the pure rolling action of bevel gears which tends to squeeze the oil film away from the contacting surfaces. tends to distribute the oil film'over the'whole of the contacting surfaces and thus to prolong-the life of the gears. These gears necessarily have teeth of of maximum strength-and of long life.

, "the line of action between a pair of hypoid, Then it was necessary to determine'f The". present invention has for-its object particularly the production of. pairs of gears, in which the pinion or smaller member is provided with teeth whose inclinatlon angle is greater than that of the teeth of the other member. In gears of this type, the

diameter or strength of the pinion is increased as compared with a bevel pinion which meshes with a gear of the same diameter and at the same ratio.

Gears formed according to this invention can be readily produced and both members may be readily ground if desired. They have the advantage of increased efficiency overworm gears and of a considerable reduction in thrusts.

The steps followed in determining what the proportions of hypoid gears should be, in order that their teeth have a gradual mesh and contact along their entire length will now be disclosed.

' It was first realized, that the desired mesh and contact could be obtained if the gears were so proportioned that their mesh would extend in the general direction of the pinion axis and that this would be the case when the projection of the pinion axis into a plane tangent to the pitch surfaces of both gears at a mean contact point was tangent to the line of action between the two gears. The next step was to determine how to locate ears. 5 how to locate a tangent to the line of action without first determnnng the hne of action.

The final step was to assume the projected pinion axis as tangent to the line of action and, from the data secured in the first two steps, determine the proportions of the, two

gears. I

' F' gs. 1, 2 and 3 illustrate diagrammaticalthe method of determining the location of the line of action between 'hypoid gears, the method of determining the location of a tangent to the line of action without first determining the line of action, and the method of determining'the proportions of the gear pair given the projected pinion axis tangent to the line of action. Referring to Figs. 1 and'2, the plane of the drawing, rep.-

rescnts a plane tangent to the pitch surfaces indicated by the numeral 10.

In development, pitch lines necessarily mcsh'like ordinary tooth profiles and are subject to the known requirements of tooth profiles. We can assume the location of the center or apex of one of the developed gears and also the longitudinal tooth curvature or longitudinal tooth profile of the gear. For a straight tooth gear the center of this longitudinal tooth curve or profile will he at infinity. To assist inthe solution of our problem, I have preferred to choose a longitudinal tooth curve or profile having a center at a finite distance and for convenience I have selected as the longitudinal tooth curve or irofile of the gear a circular are 12 having its center at 18. Ne can now determine the line of action between a gear having its apex at 11 and a mate gear whose teeth are curved longitudinally so as to mate with the longitudinal tooth curves or profiles 12 of the gear whose apex is at 11 and which is so turned in timed relation with the first gear that the rolling circles or quire can be readily determined from the.

point of contact of the pitch circles of the two gears. This oint M, which may be called the pitch-point, is the only point re quired with respect to the mate profile for determining the line 01"" action. The point 14 has, in the present instance, been assumed outside. the longitudinal tooth curve or profile, because, thereby, a general solution of the problem, Viz, to locate the line of action of a pair of hypoid gears, may be obtained. it will be understood. however, that the point 14 might have been selected on the tooth profile without efiecting our problem.

or its solution.

As is well known a pointr-of contact between mate longitudmal tooth curves or profiles may be located by drawing from the pitch point a perpendicular to the longitudinal tooth curve or profile. The intersection point between the perpendicular 15,

drawn from the pitch point 14, and the profile 12 is, therefore, a point of contact between the mate longitudinal tooth curves or profiles and hence a point of the line of action.- In the present case, the perpendicular 15 is the connecting line between the pitch point 14 and the center 13 of the pro- The: contact point 16 is determined. by

found to be an oval curve 24.

13, during the rotation of the mating gears, other points 21, 22, 23, etc. of the line of action may be located. The line of action is In Figure 1 the radius 17 has been plotted inwardly of the center of longitudinal tooth curvature 13. It might, without affecting our solution, have been plotted outwardly on the perpendicular '15.

F 1g. 2 is a diagrammatic view, corresponding to Fig. 1, in which the line of action has been determined for a pair of h poid gears one of which has straight teet to which, in particular, the present application has reference. In Fi 2, the longitudinal tooth curve or profile is taken at 25. Its center will be at infinity. As illustrated, the profile 25 is tangent to a circle 26 whose center is at- 27, the center or apex of the gear. In other words, in this case, the teeth of the gear will be non-radial or skew. 28 is the pitch point corresponding to the point 14 of Fig. 1. The line of action is again determined by drawing perpendieulars 29 through the pitch point 28 and locating the intersection points 30. The line of action is found to be a curve 31 which approaches the form of a circular are. It would be exactly a circular are if the longitudinal curve or profile 25 passed through the center 27 of the gear, that is, if the teeth of the gear Wer radial.

As before stated, the distinguishing feature of my invention is the proportioning of the mating gears so that they contact along the entire tooth surface of one member of the pair. Referring now to Figs. 4 and 5, itwill be seen that in order to have the mesh extend along the entire tooth surface of one member of the pair, the line of action should extend in the general direction of the pinion axis. In these figures, where I have illustrated one embodiment of my invention, a pair of gears is shown, consisting of a gear 32 rotatable about an axis 33 and of a pinion 34 which turns on an axis 35. The axes 33 and 35 are non-intersecting and angular-1y disposed. the shown angle between the axes being a right angle. The shortest distance 36 between the two axes, or the amount of offset-[of the two gears,will be smaller than the outside radius of the larger gear of the pair. The gears are so disposed relatively to each other that the pinion lies wholly on one side of a line drawn perpendicular to the axes of the two gears.

The gear 32 is provided with teeth 37 winch extend along radial lines 38. The sides 39 and 40 of the teeth are fiat surfaces or' planes. The sides of the teeth of the gear. therefore, are of constant profile. The teeth 41 of the pinion 34 are so constructed as to match the tooth spaces 42 of the gear.

As already stated, it can be shown readily and it is apparent from Figs. 4 and 5 that In order, therefore, to determine the'pro-" portions necessary for the two mating gears,

- to secure the desired mesh, we shall cpnsider their mesh in a plane 10 tangent to their pitch surfaces. In this plane, the projected axis of the gear is indicated at 43 (Fig, 4) and the projected axis of the pinion at 44. The projected axes intersect in this plane at the mean or common contact point 45.

eferring now to Fig. 1, it will be noted that the line of action 24 can be considered the path of a point 16 on a straight line 15 whose one end 13 moves on a circle 46 and whose other end slides on the point 14. The instantaneous axis of the straight line 15 is, therefore, on a radius 47 which passes through the center 13 of the profile 12 and the center 11 of the gear, and on a perpendicular 48 to the line 15 at the point 14. In

other words an infinitesimal portion of the motion of the straight line 15 equals a small turning motion about the point 49 which is the intersection point of the lines 47 and 48. In this motion every point of the line 15 travels perpendicularly to a radius between such point and the point 49. Hence it follows that the tangent 50 to the line of action 24 at the point 16 is perpendicular to the line 51 drawn radially from the instanta neous axis 49 to said point 16. The tangent 50 may, therefore, be located as follows:

The radius 47 is intersected with a perpen-' dicular 48, to the straight line 15 at 14. The tangent 50 is drawn through the point 16 at right angles to the line 5i connecting the points 49 and 16. This enables us to determine the location of a tangent to the line of action without first determining that line of action. The next step-in the solution of our problem requires the selection of the projected pinion axis in the plane 10 as a tan gent to tl e line of action. From this, the proportions of the two gears may be determined withont first determining the line of action. This step will be considered hereinafter.

As already noted, the solution obtained from Fig. 1 is based on the choice of a profile 12 which. for the sake of convenience, has a center at a finite distance. That the data obtained from Fig. 1 is equally applicable, however, to longitudinal tooth curves or profiles 25 which are straight is clear'from Inn " perpendicular at the pitch point 28. the point of contact 30, is at right angles to the line 56 connecting the points 53 and 30.

In Fig. 3, the pitch surfaces of the mating gears have been developed into the tangent plane 10. lhe pinion axis projected into this plane is assumed tangent to the line of action between thegtno gears. Under this condition, we know the desired mesh will )e obtained. hat remains to be dete mined, is how to determine the proportions of hypoid gears under this condition so that we can construct such gears. Given the projected pinion axis tangent to the line of action,

' We can assume, either the radius of the longitudinal tooth curves or profiles of the gear orthe distance of the pinion apex from the mean contact point 45, or any other equivalent quantity, in addition to the tooth inclination, and determine the other gear proportions.

For the purpose of ease in solution. the pitch line 57 has again been constructed so as to have a finite center. In Fig. 3, 33 is the center or apex of the gear and 59 and 60 are the projections into the'plane 10 of the gear and pinion axes, respectively. If we as sume the position of the pinion apex, We can determine the position of the profile center or radius of tooth curvature of the gear.

V ice yersa, it we assume the radius of toothcurraturc we can determinethe position of the pinion apex. Assuming the pinion apex at 58 and that 61 is the tooth normal at the point/45, that is a line which is perpendicular to the pitch line 57 of the gear, We can locate the center or radius or the pitch line.

The intersection point 62 between the line 63 connecting the gear and pinion apexcs, 33 and 58 respectively, and the tooth normal 61 is the pitch point of the pair in development; This point corresponds to the point it in Fi 1. A perpendicular 64 is erected at 62,,perpendicular to the tooth normal 61. The perpendicular 4 intersects the line 65 drawn through the point 45 perpendicular to the )lOjQCtCCl pinion axis 60 in the instantancoi s axis 66. This point 66 corresponds to the point 49 of Fig. 1 From Figs. 1 and 2 we know that the connecting line between this point 66 and the gear center or apex 33 will intersect the tooth normal 61 at the center 67 of the longitudinal tooth curve be the tooth numbers of gcr where I) is the angle included "a with respect to the ottset of the gear and pinion" axes can be determined mathematically or graphically from Figure To determine the cone angles of the pair, let a be the coneangle of the gear and a be the cone angle of the pinion, N and N I and pinion respectively. in development ie pitch surface of a gear will not occupy full circumference. The tooth number of the .ihlli circumference, in development, bears the same relation to the actual tooth number N or N as the tooth number of a crown gear is to the tooth number of a bevel gear. Hence the tooth numbers of the full circumference, in developmentof gear and pinion respec tirely, are. l

i "/l N and L sin a" as? The ratio of gear and pinion tooth numbers in development equals the ratio of the d15- tances ot' the respectute centers 33 and 58 from the pitch point 62. his known ratio is called A. Hence:

N N A Or N; sin it" sin a sin a N sin a tan a X tan a, =cos l), (2)

between the progec ted axes 59 and (30.

These two equations furnish the follofw- -mg solution:

Y O i 1 0 51112 a x/ 2 Where:

C =cotan b X A 1 1 N T C eeare b- The cone angle a" can be determined from ill) equation (3), While the coneangle a" can be (determined from either equation (1) or 2).

From the plane of Figure 3 and from the above formulas the data. for a pair of gears may be determined in'such manner that the mesh between the same extends along the whole length of the'gear teeth. This mesh will extend also over the whole or a large portion of the length of the pinion teeth. The gears moreover will be capable of sliding while in mesh, as required, and the teeth of one will match the tooth spaces of the other.

Figures 6 and 7 show diagrammatically two embodiments of my invention in which the gear has straight teeth or teeth Whose i longitudinal profile centers are at infinity,

and they illustrate the manner in which the proportions of a straight tooth pair, whose line of mesh extends substantially along the projection of the pinion axis in the tangentplane, may be deter-mined. Fig. 6 shows "diagrammatically a pair such as lllustrated 1n Figs. and 5, in'which the larger memberis provided with straight radial teeth. Fig. 7 shows the development of a pair in which the teeth of the gear are non radial or skew.

Referring to Figure 6, 68 and 69 are respectively parts of the developed pitch cones oi the gears 32 and 34, respectively. The pro ected axes are indicated at 43 and 44. In order to locatethe apex 72 of the pinion the line 73 is drawn through the gears apex 33 parallel to the normal 75. tersects line 76, which is drawn perpendicular to the projected pinion axis, at the'commen contact point 15, in apoint 77. The pro'ection of this point 77 onto the normal inrnishes the pitch point 78. The apex of the pinionis located at the intersectionof the line 79 drawn from the pitch point 78 and passing through the gear apex/33, with the projected pinion axis. j

In Figure 7, the gear is provided with teeth 80 which are non-radial orskew. 81 and 82 are parts of the developed pitch surfaces of gear and pinion respectively. 83

and 84 represent the projected axes. Line.

85 drawn through the gear apex 86: parallel to" the tooth normal 87 intersects line 88 drawn perpendicular to the projected pinion axis 84, at the common contact point 45, in the point 89. The projection of this point 89 onto the tooth normal 87 is the pitch point 90. The apex of the pinion maybe located by drawing a line 91 from the pitch point 90 through the gear apex 86 to the intersection of this line 91 with the projected pinion axis 8 1.

vFigures 8 and 9 illustrate a further embodiment of my invention in .which the gear is a crown gear 9:2, having its pitch surface in a plane and having plane tooth sides 115 and H6 of constant profile extending This line in radially of its center or apex 93. The pinion is constructed so as'to be conjugate to the gear. This pinion 94 is a cylindrical worm. The axes of gear and pinion are at 95 and 96, respectively. This particular type of gear has a much better eiliciency than worm gears. The pinion or worm is so disposed relatively to the crown gear that it lies wholly on one side of a line perpendicul' r to its axis and the crown gear axis. T e peripheral velocities of the two members, in the zone of contact, are at acute an les to one another, the angle V constituted y the peripheral velocities 'v' and o" being an acute angle. In worm' drives this angle would be a right angle. These gears have the additional advantages of the new type of hypoid gears, in that the tooth contact is superior and more intimate and in that the lines of action are more inclined to'the direction of sliding. Both these factors are assets of strength, long wear, and perfect lubrication.

Figure 10 illustrates diagrammatically the mesh of the gears shown in Figures 8 and 9. This figure, like Figures '3, 6 and 7 is a development in a plane tangent to the pitch urfaces of the two gears at a common contact point. In this figure 97 and 98 are parts of the developed pitch surface of gear and pinion respectively. 95 is the axis of the gear,'99 the projected pinion axis. As has been determined above, the line connecting the pitch point 101 with the center 93 of the gear intersects the projected pinion axis 99 in its apex When the pinion is cylindrical the line 100 will intersect the line 99 at infinity, thatis the line 100 will be parallel to the line 99. The pitch point 101 .15 located, in a manner similar to that described for the embodimentsof Figures 6 anti 7, by intersecting the tooth normal 102 with the line 100.

It should be noted with respect tojthe gears just described, that their developed.

pitch surfaces mesh like rack and gear havinga pitch line 103 and a pitch circle 104. respectively which contact at the pitch point 101. The circular pitch of the pinion equals the circular pitch of the gear at circle 104.

The gears which form the subject of this invention may be produced in any convenient manner. Preferably the gear 01' larger member of the pair is produced by causing a cutting edge to sweep across the face of the gear in such manner as to provide teeth whose side faces are of'constant profile. The gear blank will be held stationary and the tool moved in the desired direction with I preferably be formed by moving a cutting edge, representing a tooth of the gear, through the pinion blank, that is across the face thereof, while imparting a relative rolling motion between the tool and. blank in the shown in broken lines at 106, and Where the pinion 107 is rotated about its axis 108 and simultaneously moved, relatively to the tool, about the axis 109 of the gear while its apex 110 is maintained ofiset from the apex 111 of the gear. The amount of offset is determined by the method already described.

" If desired the tooth spaces of the gearanay be provided with bottoms, indicated at 112 I in Figure 4:, which are of constant width, so

that both sides 39 and 40 of a tooth space may be out simultaneously without-resorting to special machinery.

By the method described, it will be seen that the gear or larger member of the pair is non-generated and that the tooth surfaces of the pinion are molded enerated in a process in which the'pinion blank is rolled on. the gear while its axis is maintained in proper offset relation of the ear axis.

(line feature of a pair pro uced according 'to invention is the added Strength of the inion, for the same ratio, over'the usual evel pinion. This increase in strength is illustrated diagrammatically in Figure 12, Where 113 is the outline of a pinion produced according to the present invention and 114- the outline of a corresponding bevel pinion. diameter of the pinion maybe made the larger, the more its teeth. are inclined to the generatrices of its pitch surface.

' I hile my invention consists primaril in pro ortionmg a hypoid pair so that tieir toot surfaces will contact along their entire length with thetooth spaces of one member matching the teeth of, the other member along the whole length of the tooth spaces, it will he understood, that slight departures may be made from ideal conditions, as is common in gear practice, where desired, so that the pair may have some degree of adjustment or to localize the tooth bearings and that the present application is intended to cover such departures.

In general it may be said that while I have illustrated certain preferred emboditil) ments of my invention, it will be understood that this invention is capable of further modification within the limits of the dis closure and the scope of the appended claims and that this application is intended to cover any variations, uses, or adaptations of myinvention, following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in gear cutting and may be applied to the essential, features hercinbefore set forth and as fall within the limits of the appended claims.

Having thus described my invention, what I claim is: v

1. A pair of hypoid-gears, one of which is provided with straight teeth, whose cone angles, the ratio of whose tooth numbers and Whose oll'set are soproportioned as to secure contact along the entire length of the side tooth surfaces of one of the gears.

2. A pair of hypoid-gears, the larger of which is provided with radially extending teeth, and the smaller of which has longitudinally inclined teeth.

3. A pair of hypoid-gears, one of which is provided with. radially extending teeth Whose side surfaces are planes.

4. A pair of hypoid-gears, the larger of which is provided with radially extending teeth whose side surfaces are planes and the other of which is provided With longitudiinclination angle of the teeth of t e smaller member of the pair being larger than the inclination angle of the teeth of the larger member. i

7. A pair of hypoid-gears, one of which is provi ed with side tooth surfaces which lie in planes, said gears being 'constructed oint, the

to' mesh along a line of action tangent to the projected axis of one of the gears in'a' plane tangent to the pitch surfaces of both.

8. A pair of hypoid-gears so proportioned that their line of mesh exten'ds'sub,

stantially along the projection of the axis of one of the gears into a plane tangent to the pitch surfaces'df both at a mean contact point, one of said gears being provided with longitudinally straight teeth.

' 9. A pair of hypoid-gears so proportionedthat their line of mesh extends substantially along the projection of the axis of one of the gears into a plane tangent to the pitch surfaces of both at a mean contact point, one of said gears being provided with straight teeth whose side surlaces are planes.

10. A pair of hypoid-gears so proportioned that their line of mesh extends substantially along the projection of the axis of one of the gears into a plane tangent to the pitch surfaces of both at a mean contact point, one of said gears being provided with radially extending teeth.

11. A pair of hypoid-gears so proportioned that their line of mesh extends substantially along the projection of the axis of one of the gears into a plane tangent to point. one of said gears being provided with side tooth surfaces which are conjugate to plane tooth surfaces.

13. A pair of 'hypo'id'gears so proportioned that the tooth spaces of one of said gears are substantially as Wide along the whole tooth space as the teeth of the mating gear are thick, one of said gears beingprovided with tooth surfaces which are con jugate to plane side tooth surfaces.

1a. A pair of hypoid-gears so proportioned that they contact substantially along the entire length of the tooth surface of one gear, one of said gears being provided with tooth surfaces which are conjugate to plane side tooth surfaces.

15. A pair of hypoid-gears so proportioned that their line of mesh extends'substantially along the projection of the axis of one of the gears into a plane tangent to the pitch surfaces of both at a mean contact point, one of said gears being provided with radially extending teeth whose side tooth surfaces are of constant profile along their entire length and the other of said gears having teeth conjugate to those of the first gear and molded generated.

16. A pair of hypoid-gears so proportioned that the tooth spaces of one of said gears are substantially as wide along each tooth space as the teeth of the mating gear are thick, one of said gears being provided with radially extending teeth whose side molded generated.

tooth surfaces are of constant profile along their length and the other gear having teeth conjugate to those of the first gear and molded generated v 17. A pair of'hypoid-gears so proportioned that. they contact along the entire length of the side tooth surface of one gear of the pair, one of saidgearsbeingprovided with radially extending teeth whose side tooth surfaces are of constant profile along their length and the other gear having teeth conjugate to those of the.first gear and 18. A pair of hypoid-gears so proportioned that the tooth spaces of one of said gears are substantially as wide along each tooth space as the teeth of the mating gear are thick, one ofsaid gears being provided with radially extendingteeth. 4

19. A pair of hypoid-gears so proportioned thatthey contact substantially along the entire length of the side tooth surface of one gear, one of said gears being provided with longitudinally straight teeth.

20. A pair of hypoid-gears so proportioned that they contact substantially along the entire length of the side tooth surface .of one gear, one of said gears being provided with radially extending teeth.

21. A pair of hypoid-gears so proportioned that thetooth spaces of one of said gears are substantially as wide along the tooth space as the teeth of the mating gear are thick, oneof said gears being provided with longitudinally straight teeth.

22. A pair of hypoid-gears so proportioned that they contact substantially along I the entire tooth surface of one member of the pair, one of said gears having teeth whose side surfaces aret planes and the other of said gears having teeth con ugate to those of the first gear and molded generated. a

A pair of hypoid-gears so proportioned that the tooth spaces of one of said gears are substantially as wide along the whole tooth space as the teeth of the mating gear are thick, one of said gears having teeth whose side surfaces are planes and the other of said gears having teeth conjugate to those of the firstgear and molded gen.- erated.

24. A pair of hypoid-gears so proportioned as to mesh substantially along the projection of the axis of one of the gears into a plane tangent to the pitch surfaces of both at amean contact point, one of said gears being provided with teetlrot' molded generated profile.

25. A pair of hypoid-gears so proportioned that'the tooth spaces of one of said gears are substantially as wide along the whole tooth space as the teeth of the mating gear are "thick. one of said gears being proj ilded with teeth of molded generated pro 26. A. pair of hypoid-gears so proportioned as to mesh substantially along the project on of the axis of one'of said gears into a plane tangent to the pitch surfaces of both at a mean contact point, one. of said tioned that the tooth spaces of one of said gears are substantially, as wide along the whole tooth space as the-teeth of the mating gear are thick, one of said gears having side tooth surfaces which are molded generated and conjugate to plane surfaces.

28. A pair of hypoid-gears so proportioned that they contact along the entire length of the side tooth surface of one gear, one of said gears having tooth s urfaces which are molded generated and conjugate to plane surfaces.

29. A pair of hypoid-gears so proportioned as to mesh along a line of action tangent to the projected axis of one gear in a plane tangent to the pitch surfaces of both at a mean contact point, one of said gears having teeth whose surfaces are of constant profile and the other of'said gears being conjugate to the first gear and molded generated.

30. A pair ofhypoid-gears so constructed as to contact along the entire length of the side tooth surface of one gear, one of said gears having teeth of molded generated pro file.

31.; A pair of hypoid-gears so propo rtinned as to contact along the length of tie side tooth surface of one gear and so constnucted also that the inclination angle of the teeth of the smaller member of the pair is larger thanthat of the larger member of the pair, said smaller member having molded generated tooth surfaces. I

x32. A. pair of gears arranged with axes non-intersecting and non-parallel one of which a crown gear having radially extending teeth whose side tooth surfaces aria.

planes, and the other of which is a gear hay- .ing teeth conjugate to those of the crown gear and molded generated,

33.,A pair of gears arranged with axes non-intersecting and non-parallel one of which-is a crown! gear, one of said gears having teeth whose side surfaces are of constant profile and the other of said gears having teeth conjugate to the first gear and molded generated.

34. A pgi'r'of hypoid-gears so proportioned that; in a plane tangent at a common goint of contact to the pitch surfaces of 0th, a line passing through the projection of the apes of the gear and drawn from the intersection pointof a normal to the gear tooth with a line erpendic ular to said normal drawn from t is intersection point of a perpendicular to the projected pinion axis at the common contact point and a line drawn from the projection of the apex of the gear passing through the projection of the center of the longitudinal tooth curve: ture, intersects-the projected pinion axis at itsapexQ v 35. A pair of hvpoid-gears so constructed that in a plane tarl'gent to the pitch surfaces of both at a point midway the length of the contacting tooth surfaces, their ratio is proportional to the-distances of the projections of'the respective apexes of the two gears .gears.

C =cotsn b where Wu] and C =ootan b A and where b is the angle between the axes of the two gears projected into a plane tangent to their'respecti've pitch surfaces, N

and N are their respective tooth numbers and A the inverse ratio of said tooth num bers in development'in said plane.

37. A pair of gears arranged with axes non-intersecting and non-parallel, one of which is a crown gear havin radially extending teeth, whose side sur aces are nongenerated and the other of said gears h'avin teeth conjugate to the first gear and molded generated.

38.'A pair of gears arranged with axes non-intersecting and non-parallel, consisting of a crown gear having teeth whose side surfaces are non-generated and a worm having teeth conjugate to those of the crowngear,

so disposed relatively to said gears hein each other that the worm lies wholly on one side of a line perpendicular to the axes of the two gears.

39. A pair of gears arranged with; axes non-intersecting and nonparallel consisting of a crown gear, having teeth whose side surfaces are planes, and a worm, having teeth which are molded generated and con-1 jugate to those of the crown gear, said gearsbeing so disposed relatively to each other that the worm lies wholly on one side of a line perpendicular to the axes of the two 40. A pair of gears arran ed with axes non-intersecting and non-para lel, consisting of a worm and a crown gear, having radially extending teeth, said gears being disposed relatively to'each other so that the worm lies wholly on one side of a line drawn perpendicular to the axes of the two gears.

41. A pair of gears arranged with axes non-intersecting and non-parallel, consisting of a crown gear, having radially extending teeth,- and a worm, having teeth conjugate to those of the crown gear and molded generated, said gears being so disposed relatively to each other that the worm lies wholly on one side of theline drawn per- Elm pendicular to the axes of the two gears; and molded generated, said gears being so 42. A pairof gears arranged with'axea disposed relatively to each other that the nowintersecting and non-parallel, one of smaller member of the pair lies wholly on 10 whieh'is a crown gear, one of said gears one side ofa line drawn perpendicular to 1 having teeth whose side surfaces are nonhe ax s of h wo gearsgenerated, and the other of said gears havingteeth eonjegate'tofihose of the first gear ERNEST WILDHABER. 

